Drafting apron having improved frictional qualities



Dec. 24, 1968 J. E. ROBINSON 3,417,633

DRAFTING APRON HAVING IMPROVED FRICTIONAL QUALITIES Filed Nov. 27, 1964 INVENTOR JAMES E- ROBINSON Y ZQLQJWZMQ ATTORNEY United States Patent 3,417,633 DRAFTIN G APRON HAVING IMPROVED FRICTIONAL QUALITIES James E. Robinson, Lancaster, Pa., assignor to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania Filed Nov. 27, 1964, Ser. No. 414,183 5 Claims. c1. 74 232 This invention relates to elements used in the processing of textile fibers and particularly to drafting aprons. The invention will be described with particular reference to long draft spinning aprons but it will be understood that the invention is not limited thereto and may be advantageously utilized wherever the unique properties of the invention are required, such as low speed drive belts, etc.

A fiber drafting apron is an endless belt or flexible sleeve having an outer fiber contacting surface. In use, at least one such apron is normally mounted in operating position over a rearwardly located driving roller and a forwardly located stationary supporting rod or nose bar and is held in an elongated shape by said driving roller and nose bar to provide a planar apron surface for contacting the fiber. A second apron or roller is normally mounted in closely spaced relationship with the first apron for cooperation therewith to simultaneously grip the fibrous strand on both its top and bottom. These aprons are employed in currently used drafting systems such as the Saco Lowell-Roth, Duo Roth, and the Whitin- Casablancas systems. In these systems, the drawing or drafting of the fibers is generally achieved by passing them through a series of nearly tangentially contacting rollers and/or aprons, the peripheral speeds of which increase successively throughout the series so that those pairs which are forward or in the direction of travel of the sliver will tend to pull and draw out the strand while the rollers and aprons rearwardly thereof will act as a brake thereon. A pair of cooperating aprons or an apron operating in combination with a roller are normally positioned between front and back pairs of drafting rolls in these systems and serve to support and control the loose fibers passing therethrough over a considerable portion of their length as they move from the back pair of rolls into the nip of the front pair of rolls. This is accomplished by causing the aprons and/or the apron and roller to be closely spaced along a portion of their respective surfaces at which point the opposed surfaces move in the same direction. Since the frictional characteristics of the inner surface of the inner ply of the apron must be such that it can be positively driven and the driving roller for the apron is positioned to the rear of the stationary nose bar, the apron, in operation, is in effect partially pushed over the nose bar and there is a tendency for the apron to chatter or vibrate. The vibration of the apron results in variations in the spacing between the cooperating aprons or apron and roller which in turn cause nonuniformity in the thickness of the strand being formed. Because of their nonuniform cross-sectional dimensions, the strands of thread or yarn become difficult to process or weave. Additionally, there has been a noticeable tendency for the synthetic rubber aprons to become damaged or destroyed because of failure of the apron to move freely over the stationary supporting bar in the Whitin-Casablancas, the Saco Lowell-Roth, Duo Roth, and other similar systems; the physical characteristics of the inner surface of the aprons impairing their movement over the stationary surface under usual drafting tension and conditions of temperature and humidity normally encountered in spinning rooms.

It has long been desirable to have a drafting apron, the

3,417,633 Patented Dec. 24, 1968 inner surface of which would freely slide over the stationary surface of a nose bar and yet have a high enough coefficient of friction to enable it to be efficiently driven by a rearwardly positioned drive roll.

Attempts have been made in the past to alter the surface characteristics of textile cots and aprons by adding various chemicals to the rubber compound along with the other components such as fillers, sulphur, antioxidants and vulcanizing accelerators. In US. Patent 2,729,860, for example, a surface active agent or a mixture of surface active agents is added to the rubber compound from which an article is then formed. The surface active agent is said to impart an antilicking character to the article.

As disclosed in U.S. Patent 3,011,221, it is also known to provide a fiber drafting apron which will pass over the stationary rod or nose bar such as in the Whitin- Casablancas, the Saco Lowell-Roth, and Duo Roth systems with a minimum of vibration. This is said to be achieved by incorporating a physically and chemically inert lubricant in the material forming the innermost surface of the apron which comes in contact with the nose bar. The fluorocarbon lubricant used is completely inert, is miscible but not compatible in any way with the synthetic rubber, and is dispersed uniformly throughout the entire material and is present at the innermost apron surface formed thereby to permanently remove any residual tack that is otherwise inherent in such a compound.

Prior attempts to correct deficiencies in textile aprons have not supplied a solution to the problem of providing the inner ply of a textile apron with a surface which will readily slide over a stationary nose bar without vibrating or chattering and yet have a coefiicient of friction high enough to enable it to be driven by a rearwardly positioned drive roll.

It is an object of the present invention to provide an improved element for textile working machinery. It is a more specific object of the present invention to provide an improved apron for use in fiber drafting machinery wherein the apron slides over a stationary supporting rod or nose bar such as in the Whitin-Casablancas, the Saco Lowell-Roth, and Duo Roth systems. It is still another object of the present invention to provide a fiber drafting apron which will pass over the nose bar with a minimum of vibration. It is a still further object to provide such a drafting apron having an inner ply containing an additive which substantially eliminates vibration of the apron when it passes over the nose bar. A still further object is to provide such a drafting apron which accomplishes the foregoing without sacrificing the necessary frictional qualities of the inner ply thereof which allow the apron to be driven without slippage.

This invention accomplishes the foregoing objects by providing a two-ply fiber-contacting element for use in processing textile fibers which is composed of an outer fiber-contacting layer of a synthetic rubber composition and an inner layer composed of a synthetic rubber composition containing as a permanent ingredient in the proportion of 1 to 6 parts by weight to parts by Weight of synthetic rubber, an additive comprising alkali metal salts selected from the group consisting of aliphatic sulfates, aliphatic sulfonates and mixtures thereof. The additive used in the formation of the inner ply has the property of imparting a surface characteristic thereto which does not impair its frictional qualities allowing it to be easily and efiiciently driven by a rearwardly positioned drive roll and yet makes it possible for the apron to pass over the nose bar with a minimum of grabbing or vibration.

Prior apron compositions containing lubricants reduced the coefficient of friction thereof and while they eliminated to some extent the objectionable chattering or vi- 3 brating of the apron as it passed over the nose bar, it made driving of the apron by the rearwardly positioned drive roller less efficient.

The results of this invention were completely unobvious drawing rollers 12 and 13. Then the strand passes through the closely spaced, parallel surfaces of the fiber drafting aprons 14 and 15 which are counter rotating so that the opposed surfaces are both moving in the direction of the since one would normally, and especially in. view of the 5 sliver. Thereafter the strand passes through the bite 16 prior art, consider it necessary to reduce the coefficient of the front drawing rollers 17 and 18. The drawing rollers of friction of the inner surface of the apron to eliminate 12, 13, 17 and 18, or at least one of each pair of such grabbing or vibrating of the apron as it passes over the rollers, are preferably provided with a relatively soft or stationary nose bar. An example of this is shown in aforedeformable surface such as one composed of synthetic mentioned US. Patent 3,001,221 which, as previously rubber so that the rollers in each pair will grip the strand stated, makes use of an inert lubricating material which, and make the sliver speed dependent upon the peripheral due to its incompatibility with the other ingredients of the speed of the rolls. In this manner, the peripheral speed compound used to form the inner ply of the apron, exudes of the rear rollers 12 and 13 may be made to be less than out and forms a friction reducing covering for the surface that of the aprons 14 and 15 which in turn will be made portion of the inner ply. In addition, the compatibility of 15 to travel much more slowly than the front drawing rollers the present additive with the other ingredients of the com- 17 and 18 so that between each successive pair of rollers pound would lead one to think of it as merely a softener and aprons, the sliver 10 will be more finely drawn and or a plasticizer. closely compacted preparatory to its entering upon the The present invention solves the problem of providing spinning or twisting operation after leaving the front drawa finished rubber apron adapted for continuous move- 20 ing rollers 17 and 18. merit over a stationary metal surface without chattering As previously stated, the aprons 14 and 15 are driven or vibrating while the apron is in a partially relaxed conby at least one of the vertically opposed rolls 19 or 20. dition due to a driving arrangement in which the driving In most cases just one of these rollers, usually the lower roll is located to the rear of the stationary metal surface. roller 20, is powered and its contact with the apron 15 Additionally, the invention is concerned with accomplishand the contact of the apron 15 with the apron 14 will ing the foregoing without sacrificing the desirable fricset the entire apron assembly including the upper apron tional qualities of the inner surface of the apron which 14 and the apron roller 19 in motion. The lower apron allow it to be positively driven by the rearwardly mount- 15 will move in a clockwise direction and the upper ed drive roll without slippage. apron will move counter-clockwise so that the opposed,

It is not completely understood how the improved reparallel and closely spaced fiber-contacting areas 21 and sults are obtained but it is believed that the additive may 22 will move in the same direction along with the sliver be protecting the inner surface of the apron from mois- 10. To hold the aprons in an extended position and mainture conditions caused by high humidity of spinning tain the surfaces 21 and 22 in taut parallel relationship, rooms. the drafting machinery provides the supporting rods or The additive may be added to the stock from which the nose bars 23 and 24, and idler roll 25. The forward surinner ply of tthe textile apron is formed, at the compoundfaces of the nose :bars 23 and 24 are rounded and smooth ing and mixing stage, in the amounts ranging from 1 to 6 to allow the apron to slide freely thereover, the bars themparts per 100 parts by weight of the other materials used. selves being stationary.

Some typical recipes illustrating the use of the additive These nose bars 23 and 24 are so spaced that the optogether with other ingredients used in the stock for formposed parallel apron surfaces 21 and 22 will at least gently ing the inner ply of a textile apron are as follows: contact the fibrous strand passing between them. Where PARTS BY WEIGHT Butadiene-acrylonitrile copolymer .0 100.0 100.0 100.0 100.0 100 0 100 0 100.0 1000 Bone glue .0 30.0 30.0 30.0 30.0 Plasticizing system. .5 16.5 10.5 10.5 16.5 10.5 10.5 10.5 16.5 SRF black .3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Fillers and i ments. .0 35.0 35.0 35.0 55.0 35.0 55.0 05.0 05.0 Sulphur containing cur g system 4.6 4.0 4.0 5.0 5.0 3.5 5.5 0.7 0.7 Additive 1.0 2.0 4.0 2.0 4.0 2.0 2.0 2.0 4.0

3.7% decyl sodium sulfate, 0.8% stearyl sodium sulfate, 1.0% merts.

In all of these stocks, the addition of the additive reduces the friction between the innerliner and the steel pin or nose bar. This effect is most noticeable in the stocks having a low sulphur content. In these stocks the reduction in friction is reflected in less wear and elimination of hopping and chattering of the apron. In the above compositions, the minimum amount of the additive found to be effective was 1 part by weight of the additive to 100 parts by weight of the rubber. The optimum level of the additive was found to be from 2 to 4 parts to 100 parts by weight of rubber. Although I to 6 parts of the additive may be used, very little apparent improvement was obtained by the use of more than 4 parts of the additive.

In the drawings:

FIGURE 1 is a schematic elevational view of a Duo Roth system fiber drafting unit in connection with which drafting aprons according to the present invention may be advantageously employed, and

FIGURE 2 is an enlarged fragmentary perspective view showing an apron according to the present invention as it passes about a nose bar.

In FIGURE 1, the sliver or loosely compacted fibrous strand 10 moves in the direction of the arrows through the bite 11 of the substantially tangentially contacting aprons of a thickness on the order of .032 inch are employed, it has long been the practice to space the nose bars vertically by a distance of from 7 to 8 millimeters. More recently however, this spacing has been reduced to from 4 to 5 millimeters. While this closer spacing has resulted in improved and quicker drafting, it has enhanced the deleterious effect of the chattering or vibration of the aprons as they are forced by the rear drive over and around the bars.

As shown in FIGURE 2, one preferred embodiment of the present invention is a drafting apron composed of an outer layer 26 of an elastomeric material, such as rubber or a synthetic rubber of the kind normally used in drafting aprons, which provides an outer fiber-contacting surface 27. The apron also comprises an inner layer 28 of an elastomeric material such as a butadiene-acrylonitrile copolymer with which preferably from 1 to 4 parts by weight of the additive to parts by weight of the rubber are compounded. This inner layer presents the innermost surface 29 of the apron sleeve which is that contacted by a driving roller such as 20 in FIGURE 1 and makes sliding contact with the surface 30 of the nose bar 31. It is at this point that the characteristics of the surface 29 of inner layer 28 become critical.

If it is desired to reinforce the apron against longitudinal extension, an intermediate layer of helically Wound inextensible cord such as cotton or rayon may be employed. Where a two-layer construction is employed, the innermost layer may be composed according to the present invention to provide the improved inner surface qualities sought hereby, while the outermost layer may be compounded exclusively for improved fiber contact and drafting without any such additive therein.

In the manufacture of aprons according to the present invention, the elastomeric material for the outer layer is compounded according to usual practice, as in an internal mixer or on a mill, and is then calendered into a sheet or layer of suflicient gauge to provide the desired thickness after grinding or other finishing. As previously stated, the outer layer may be an elastomeric material such as a rubber or synthetic rubber of the type normally used in drafting aprons. The inner layer is formed as described above. However, it is important in the compounding of the inner layer that the additive be introduced as the compounding and mixing stage so that it will .be uniformly mixed and distributed throughout the entire stock.

The layers thus formed may be wrapped about a suitable building mandrel, the inner layer of course being first wrapped, and then the outer layer. The apron sleeve thus laminated is then compacted as for example by rag wrapping and subjected to conditions of heat and/ or pressure for vulcanization and finishing.

I claim:

1. A textile fiber drafting apron having inner and outer layers of synthetic rubber, said inner layer having dispersed throughout the body thereof, an additive comprising alkali metal salts selected from the group consisting of aliphatic sulfates, aliphatic sulfonates and mixtures thereof, said salts containing 10-16 carbon atoms, said additive being compatible With said inner layer rubber and present therein in the range of from 1 to 6 parts by weight of the additive to parts by weight of the rubher, said additive imparting a surface characteristic thereto which does not impair its frictional qualities, allowing it to be easily and efficiently driven by a rearwardly positioned drive roll and making it possible for the apron to pass over a nose bar with a minimum of grabbing or vibration.

2. A textile fiber drafting apron according to claim 1 wherein the rubber in said inner layer is a lbutadieneacrylonitrile copolymer.

3. A textile fiber drafting apron according to claim 1, wherein the rubber in said inner layer is a butadienestyrene copolymer.

4. A textile fiber drafting apron according to claim 1 wherein the additive comprises lauryl sodium sulfate.

5. A textile drafting apron according to claim 1 wherein the additive comprises myristyl sodium sulfate.

References Cited UNITED STATES PATENTS 2,402,356 6/ 1946 Bacon et a1. 19244 2,729,860 1/1956 Balkin et al 26030.8 3,011,221 12/1961 Howell 19244 ROBERT F. BURNETT, Primary Examiner.

R. I. ROCHE, Assistant Examiner.

US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,417,633 December 24 1968 James E. Robinson It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 10, "3,001,221" should read 3,011,221 line 36, "tthe Columns 3 and 4, in the table, sixth and seventh should read the same line 5, "35. 0"

columns, line 5 thereof, "55.0" should read 35.0 should read 55.0

Signed and sealed this 17th day of March 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer 

1. A TEXTILE FIBER DRAFTING APRON HAVING INNER AND OUTER LAYERS OF SYNTHETIC RUBBER, SAID INNER LAYER HAVING DISPERSED THROUGHOUT THE BODY THEREOF, AN ADDITIVE COMPRISING ALKALI METAL SALTS SELECTED FROM THE GROUP CONSISTING OF ALIPHATIC SULFATES, ALIPHATIC SULFONATES AND MIXTURES THEREOF, SAID SALTS CONTAINING 10-16 CARBON ATOMS, SAID ADDITIVE BEING CAPATIBLE WITH SAID INNER LAYER RUBBER AND PRESENT THEREIN IN THE RANGE OF FROM 1 TO 6 PARTS BY WEIGHT OF THE ADDITIVE TO 100 PARTS BY WEIGHT OF THE RUBBER, SAID ADDITIVE IMPARTING A SURFACE CHARACTERISTIC THERETO WHICH DOES NOT IMPAIR ITS FRICTIONAL QUALITIES,, ALLOWING IT 